This disclosure relates to selecting embedded cells in wireless networks.
Cellular wireless communications systems are designed to serve many access terminals distributed in a large geographic area by dividing the area into cells, as shown in FIG. 1. At or near the center of each cell 102, 104, 106, a radio network access point 108, 110, 112, also referred to as a base transceiver station (BTS), is located to serve access terminals 114, 116 (e.g., cellular telephones, laptops, PDAs, also known as mobile stations) located in the cell. Each cell is often further divided into sectors 102a-c, 104a-c, 106a-c by using multiple sectorized antennas. In each cell, that cell's radio network access point may serve one or more sectors and may communicate with multiple access terminals in its cell. In the example of FIG. 1, the access points are connected over a backhaul connection 118 to radio network control/packet data serving nodes (RNC/PDSN) 120, which may be one or more physical devices at different locations.
The 1xRTT protocol has been standardized by the Telecommunication Industry Association (TIA) in the TIA-2000.1 through TIA-2000.6 series of specifications, which are incorporated herein by reference.
The 1xEV-DO protocol has been standardized by the Telecommunication Industry Association (TIA) as TIA/EIA/IS-856, “CDMA2000 High Rate Packet Data Air Interface Specification,” 3GPP2 C.S0024-0, Version 4.0, Oct. 25, 2002, which is incorporated herein by reference. Revision A to this specification has been published as TIA/EIA/IS-856A, “CDMA2000 High Rate Packet Data Air Interface Specification,” 3GPP2 C.S0024-A, Version 2.0, July 2005. Revision A is also incorporated herein by reference. Other wireless communication protocols may also be used.
The UMTS and HSDPA protocols (W-CDMA) have been standardized by the Third Generation Partnership Project (3GPP). Specifications relevant to this disclosure include 3GPP TS 23.003 v7.4.0, 3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Numbering, addressing and identification (Release 7); 3GPP TS 25.304 v7.2.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; User Equipment (UE) procedures in idle mode and procedures for cell reselection in connected mode (Release 7); and 3GPP TS 25.331 v7.5.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Radio Resource Control (RRC); Protocol Specification (Release 7).
When connecting to a radio network, an access terminal selects an access point from a list of available radio network access points that are known to be within communication range. In conventional CDMA systems, the access terminal obtains the list of available access points from “neighbor list information.” In general, neighbor list information includes the set of radio channels (e.g., radio access technology, band classes, frequencies, and channel bandwidths) and other necessary information (such as timing offsets, coding information, details about the particular radio technology in that channel, search window size, etc.) to assist the access terminal in locating radio network access points from which it can potentially receive radio services.
Neighbor list information is typically provided to the access terminal via (1) a preconfigured database programmed into the access terminal in a static or semi-static (infrequently updated) state or (2) overhead signaling messages that are transmitted by some or all of the radio network access points located within the general vicinity of the access terminal. These mechanisms for providing neighbor list information to an access terminal are generally implemented on static radio access networks in which the locations of radio network access points are either permanently fixed or changed infrequently.